Physical vapor deposition is often utilized for a variety of applications. For instance, different data media, such as CD and DVDs are coated in a physical vapor deposition process. But also foils, tools and microelectronic devices are produced by this method. Chambers for physical vapor deposition optionally include a substrate, on which a material is to be deposited and a target, from which the material stems.
Almost all metals can be used as material to be deposited. A process gas is introduced in a physical vapor deposition chamber. Often, the target is used as a cathode and the substrate is used as an anode. By applying a voltage between anode and cathode, the gas there between becomes plasma. The particles in the plasma of the process gas can react with the target and release particles from the target material. The particles of the target material are deposited on the surface of the substrate.
When the deposition material of the target is exhausted, the target has to be removed from the chamber and has to be replaced by a new target. Also, the chamber has to be cleaned from time to time, thereby removing the target material, which was not deposited on the substrate but on parts of the chamber (for instance chamber walls, target periphery etc.) due to spreading of the target material particles.
The step of removing the target and mounting it again after the periphery of the target or the target itself has been replaced, occupies a certain amount of the time needed for maintenance of the chamber. Thus, long-life targets and process conditions limiting the spreading of material to a certain amount are common means for preventing too much loss of production time.